2014-01-11

Hello Cassandra in node.js

Intro

Since I started to work in a team that deals with BigData stuff I came into contact with Apache Cassandra. After years in the relational world it took me some getting used to the many concepts that the Cassandra relies on. Actually in the relational world the concepts would be heavy anti patterns. I went over a couple of tutorials etc. for intro into the Cassandra data model I would recommend this video by Patrick McFadin:

C* Summit 2013: The World's Next Top Data Model


Basic setup

The easiest way to get the Cassandra is to download it from here: http://planetcassandra.org/Download/StartDownload

I somehow dislike when various applications write to /var/something and having to use the root access to install something unless it's absolutely necessary. So I followed this manual to avoid this problem.


cassandra.yaml

The Cassandra is setup out of the box to support queries coming from cql shell ("cqlsh"). The goal of this blog entry is to show how to make a simple connection from node.js to the Cassandra, so there is a bit of tweaking that has to be done in order to get all this working. The necessary configuration is located in this file:

 install_dir/conf/cassandra.yaml
The properties I had to change were (basically this allows logging in with users other than default):
 authenticator: PasswordAuthenticator
 authorizer: CassandraAuthorizer
After that going into bin directory and running cqlsh will require username & password
 ./cqlsh -u cassandra -p cassandra

Cassandra keyspace setup

 CREATE KEYSPACE test WITH REPLICATION = 
  {'class': 'SimpleStrategy', 'replication_factor': 1};

 --check if it's created with this
 DESCRIBE KEYSPACES;

 USE test;

 CREATE TABLE test_table (
  id text,
  test_value text,
  PRIMARY KEY (id)
 );

 INSERT INTO test_table (id, test_value) VALUES ('1', 'a');

 INSERT INTO test_table (id, test_value) VALUES ('2', 'b');

 INSERT INTO test_table (id, test_value) VALUES ('3', 'c');

 SELECT * FROM test_table;
 
If everything is o.k. you should see something like:
  id  | test_value
 ----+------------
   3 |          c
   2 |          b
   1 |          a

 (3 rows)
Add a testuser to make the hello world example work:
  create user testuser with password 'testuser';

  grant all on test.test_table to testuser;

node-cassandra-cql

I tried several Cassandra connection libraries from gitHub for the node.js and the one that I found most easy to work with (and setup) was node-cassandra-cql by jorgebay. The story with the project is pretty much standard. Going into new project empty directory and initializing it with init and then installing module with npm.

 npm init

 npm install node-cassandra-cql

 #copy hellocassandra.js from
 #https://github.com/msval/hellocassandrainnodejs

 node hellocassandra.js
 

Anyway here's my example on gitHub.

4 comments:

Anonymous said...

it looks like you are rather using node-cassandra-cql rather than node-cassandra-client, thus the package is problably the wrong one in the tutorial?

Marko Švaljek said...

you are right! I probably copy-pasted it from wrong tab while I was writing ;) thank you so much!

Cassandra DB Developers said...

The content is good and very informative and I personally thank you for sharing nodejs articles with us.

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